Group III Nitride Semiconductor Light Emitting Device

• US 20070228407A1
• Filed: 05/20/2005
• Published: 10/04/2007
• Est. Priority Date: 05/24/2004
• Status: Active Grant

• Current Assignee: Showa Denko KK
• Original Assignee: Showa Denko KK
• Inventors: Takeda, Hitoshi, Horikawa, Syunji
• Granted Patent: US 7,456,445 B2
• Time in Patent Office: Days
• US Class Current: 257/101
• CPC Class Codes: H01L 33/305 characterised by the doping materials
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/325 characterised by the doping materials

Abstract

A Group III nitride semiconductor light emitting device having a light emitting layer (6) bonded to a crystal layer composed of an n-type or p-type Group III nitride semiconductor, the Group III nitride semiconductor light emitting device being characterized by comprising an n-type Group III nitride semiconductor layer (4) having germanium (Ge) added thereto and having a resistivity of 1×10⁻¹ to 1×10⁻³ Ωcm. The invention provides a Ge-doped n-type Group III nitride semiconductor layer with low resistance and excellent flatness, in order to obtain a Group III nitride semiconductor light emitting device exhibiting low forward voltage and excellent light emitting efficiency.

Claims

1. A Group III nitride semiconductor light emitting device having a light emitting layer bonded to a crystal layer composed of an n-type or p-type Group III nitride semiconductor, the Group III nitride semiconductor light emitting device being characterized by comprising an n-type Group III nitride semiconductor layer having germanium (Ge) added thereto and having a resistivity of 1×

10<sup>−

1</sup> to 1×

10<sup>−

3</sup> Ω

cm.

2. A Group III nitride semiconductor light emitting device according to claim 1, wherein the n-type Group III nitride semiconductor has the compositional formula Al_xGa_yIn_zN_1-aM_a (wherein 0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1, x+y+z=1, M represents a Group V element other than nitrogen (N) and 0≦

a≦

1).

3. A Group III nitride semiconductor light emitting device according to claim 1, wherein the Ge-added n-type nitride semiconductor layer is a Group III nitride semiconductor layer including a region in which the Ge atom concentration varies in a periodic manner.

4. A Group III nitride semiconductor light emitting device according to claim 1, wherein the region in which the Ge atom concentration varies in a periodic manner is composed of a structure with periodic alternating lamination of the Ge-added Group III nitride semiconductor layer and an undoped Group III nitride semiconductor layer.

5. A Group III nitride semiconductor light emitting device according to claim 1, wherein the layer thickness of the Ge-added Group III nitride semiconductor layer is equal to or less than the layer thickness of the undoped Group III nitride semiconductor layer.

6. A Group III nitride semiconductor light emitting device according to claim 1, wherein the Ge atom concentration in the Ge-added Group III nitride semiconductor layer is at least 1×

10¹⁷ cm<sup>−

3</sup> and no greater than 1×

10²⁰ cm<sup>−

3</sup>.

7. A Group III nitride semiconductor light emitting device according to claim 1, wherein the n-type Group III nitride semiconductor layer is situated between a substrate and the light emitting layer.

8. A Group III nitride semiconductor light emitting device according to claim 3, wherein the total layer thickness in the region in which the Ge atom concentration varies in a periodic manner is at least 0.1 μ

m and no greater than 10 μ

m.

9. A Group III nitride semiconductor light emitting device according to claim 3, wherein the layer thickness of one period in the region in which the Ge atom concentration varies in a periodic manner is at least 1 nm and no greater than 1000 nm.

11. An LED employing a Group III nitride semiconductor light emitting device according to claim 1.

12. A lamp employing a light emitting device according to claim 11.

10. A process for fabrication of a Group III nitride semiconductor light emitting device having a light emitting layer bonded to a crystal layer composed of an n-type or p-type Group III nitride semiconductor, the process being characterized in that during growth of the Ge-added n-type Group III nitride semiconductor layer, Ge atom is supplied to the reaction system in a periodically varying manner.